The invention relates to a lubricating oil dosing arrangement for the valves of an internal combustion engine, wherein the valves have valve shafts and are movably in guide bores formed in the cylinder head of the internal combustion engine.
Conventional reciprocating piston engines include cylinders with cylinder heads in which inlet and outlet valves are movably supported in cylindrical guide bores, so that they are subject to wear which is minimized by the addition of lubricant. For minimizing the wear of the valve shafts, engine oil is supplied by a dosing pump from the oil circuit of the engine to the inlet valve shafts or, via passages, directly to the valve guides, particularly the outlet valve guides. For reducing noxious emissions caused by the combustion of excessive amounts of lubricating oil and for reducing blow-by air, air fuel mixture or exhaust gas to flow out of the cylinder of the internal combustion engine through the gap between the bore and the valve caps, O-rings are installed as seals on, or in, the valve shaft guide bores in today's piston engines.
G 90 00 671.2 discloses a lubrication arrangement for valves of a piston engine wherein, for the control of the lubricant passing between the valve shaft and the bore, a seal ring with a seal lip is provided.
JP 59 049307 discloses a lubrication arrangement for valves which includes seal rings arranged between the valve shaft and the cylindrical guide bore. The seal ring is arranged axially movably in a groove of the cylindrical bore and is moved back and forth in the groove by the valve shaft by friction with each valve lift for the transport of lubricant. Lubricant is pumped from a larger upper gap to a lower smaller gap along the valve shaft and the cylindrical guide bore.
DE 29 35 260 A1 discloses a seal for mounting onto the end of a cylindrical guide projection of a valve shaft guide bore structure. This seal includes a rigid seal body with an annular guard plate, which surrounds the guide projection, an upper essentially cylindrical wall, which is connected to the annular guide plate, a radially inwardly extending web at the inner surface of the wall and an elastic insert having an outer annular groove accommodating the rib, wherein between the rib and the outer annular groove an oil reservoir is provided. Upon back and forth movement of the valve shaft, the elastic insert is moved along with the valve by friction and opens and closes the oil reservoir between the rib and the outer annular groove upwardly for supplying oil from the valve drive and downwardly for admitting oil to the gap between the valve shaft and the cylindrical bore in direction toward the valve seat.
DE 28 28 981 A1 discloses a valve shaft seal at the end of a cylindrical valve guide projection wherein an annular sleeve section surrounds a valve guide section. A transversely extending wall is disposed at the upper end of the valve guide projection and sealingly abuts the valve shaft. The transversely extending wall includes an inner surface provided with two-axially spaced annular seal sections which are separated from an annular groove disposed adjacent the upper end of the valve guide projection. The underside of the transverse extending wall intersects the lower seal section in such a way that a sharp edge is formed. An inner surface which is inclined upwardly and outwardly extends to the upper side of the transversely extending wall and causes a capillary oil flow to the seal sections.
The valve shaft seals of the state of the art detrimentally affect to a different degree the lubricant supply to the valve guide structures and, at least for the inlet valves, also the lubricant supply to the valve disk which may result in an increased wear of the valve shaft, the valve guide, the valve disk and/or the valve seat ring. Particularly the dosing of the lubricant amount for each valve guide is unsatisfactory and/or the costs of such lubricant supply arrangements are excessive.
It is the object of the present invention to provide a technically simple and therefore inexpensive lubricant dosing arrangement for valves by which to each valve in the cylinder heads of piston engines a predetermined amount of lubricant can be supplied.